There is evidence that moral behavior is a product of evolution and an innate aspect of the human brain. Functional magnetic resonance studies in normals, investigations of psychopaths, and acquired sociopathy from brain lesions suggest a neurobiology of moral behavior. Reports of sociopathy among patients with frontotemporal dementia (FTD) have provided a further opportunity to clarify the neurobiology of morality. They confirm a morality network that includes the ventromedial frontal cortex, the orbitofrontal cortex, and the amygdalae. The right ventromedial region is critical for the emotional tagging of moral situations, the orbitofrontal cortex responds to social cues and mitigates impulsive reactions, and the amygdalae are necessary for threat detection and moral learning. Alterations in moral behavior in FTD may result from a loss of the emotional label of moral dilemmas, coupled with disinhibited responses. More investigations are needed to fully understand how the brain mediates moral or ethical behavior.